Problem with piranha EXT

ok so i recently bought a piranha EXT by pmi from a guy off craigs list for about bought a gear bag also a 9 ounce co2 tank by brass eagal, 32 degrees whisper barrel 14'', gloves, pod pack, 3 pods along with a piranha vtl or something like that,and a WPG autocker both non woring though all for 80$ is that a good deal ? sorry about that that was just something on my mind at the time

my real question is about the ext its leaking co2 out of the barrel i think it may be the cup seal or maybe just and o-ring is broken but i have no clue which if anyone knows what els i should chek ive already taken it apart and replaced most of the o-rings and heres some picks of how far ive been able to take it apart with my current knowlage of the gun

and i just took the guys word that it was the ext ive searched it it looks like it but if its not please tell me.

and sorry about the pics being huge and kinda bad quality if they are did this off my phone also sorry for bad grammar and spelling

gun together

asa off and sprng thing with pin and 4 pointed star thingy

now with bolt and hamer out and seperated

close up of bolt hammer asa and wired star spring thing

if you want any pics of anything els please tell me and ill try to get it to you btw thats all i know how to take off so far so if its something inside the regulator or the valve thing that the star spring goes in idk how to take them out so ill need some help with that

I own the same gun, bought it brand new back in 2006, used it for 2 year till i got married then i couldnt use it any more because it leaked from the reg. i kept it in my closet and a week ago completely took it apart and very single o-ring was ruined! i can replace most of them, but i am a bit concerned about the striker's o-ring but really worried about the ones inside the reg.

i just dont know what to do, im looking forward to play ball again and i would be great not to be forced to rent or buy a new marker.